This invention relates to a process for applying indicia to adhesive tapes. More particularly, the invention relates to a process for applying permanent, non-removable indicia to pressure-sensitive tapes utilizing vapor transfer of a heat-sublimable dye.
Conventional pressure-sensitive tapes typically comprise a substrate or support upon which the pressure-sensitive adhesive is coated. To avoid specific problems, it is common to provide a backsize coating on the opposite side of the support. Such backsize layers may comprise low adhesion release materials, abrasion-resistant materials, solvent barrier-protective backsizing, etc.
In many instances, it is desirable to provide such an adhesive tape with indicia for identification, directional, instructional or merely informative purposes. Such is especially true in the area of carton sealing tapes for cartons which are used to transport merchandise therein by commercial transportation methods. Tapes having indentifying indicia thereon would greatly assist manufacturers, shippers and purchasers. However, such tapes and any indicia thereon must be able to withstand the rigorous treatment normally encountered in the handling and transportation of the carton.
Vaporizable dyes have long been utilized in fabric decorating, wherein patterns or designs are obtained on fabrics, such as textiles, by transfer of volatile dyes from patterns on a transfer sheet to the fabric. Typically, the dye design on a transfer sheet is placed against the fabric and heat and limited pressure are applied. The dyes sublime to vapor form and are transferred from the transfer sheet to the fabric with the dye design intact.
Belgain Pat. No. 807,975 discusses preparation of stencils for use with dye transfer so as to avoid necessity of requiring a transfer sheet having a dye design thereon.
In U.S. Pat. No. 3,860,388 there is disclosed a process for transferring a dye pattern from a transfer sheet to a thermoplastic surface. A polyolefin sheet is interposed between the transfer sheet and the plastic receiving surface which when heated to its softening temperature allows passage of the dye vapors therethrough, and effectively prevents fusing of the dye transfer sheet to the thermoplastic surface at the elevated dye sublimation temperature.
While it would be extremely desirable to imprint backsized pressure-sensitive tapes with smudge-proof permanent indicia, such has heretofore not been available. Common methods for imprinting indicia on tapes do not provide images which are sufficiently durable for such tapes as carton sealing tapes. It has now been found that by utilizing sublimable dyes and dye vapor transfer, imprinted tape having the aforementioned desirable characteristics can be obtained.